Body Composition in Very Preterm Infants: Role of Neonatal Characteristics and Nutrition in Achieving Growth Similar to Term Infants

Abstract

Background: The identification of factors involved in the postnatal growth of preterm infants will help achieve growth similar to that of term infants. Objectives: As per protocol: to compare body composition in very preterm infants at term-corrected age (TCA) with that in term infants, and to explore relationships between neonatal characteristics and body composition in preterm infants. Methods: Anthropometry, nutritional characteristics, and neonatal outcomes were prospectively collected in 26 preterm (<29 weeks) and 33 term (37-40 weeks) infants. Body composition using dual-energy X-ray absorptiometry (DXA) was measured at TCA in preterm infants and between days 7 and 10 in term infants. Results: Parenteral nutrition in preterm infants provided a mean of 2.9 ± 0.2 and 2.1 ± 0.5 g/kg/day of intravenous amino acids and lipids, respectively, during the first week of life. The mean weight gain velocity from birth to DXA assessment was 12.1 ± 1.4 g/kg/day. Compared with term infants, preterm infants at TCA were shorter and lighter, with a smaller head circumference, a lower weight estimated by DXA (2,960 ± 552 vs. 3,843 ± 377 g), and increased skinfold thicknesses. Fat mass percent (13.9 ± 5.4%) and lean mass percent (84.7 ± 5.6%) in preterm infants were similar to those in term infants (14.7 ± 3.5 and 83.5 ± 3.6%, respectively). Neonatal weight gain velocity in preterm infants was positively associated with lean mass (grams). Conclusion: Subcutaneous fat is increased in preterm infants. Higher protein intake in preterm infants might increase weight gain velocity and achieve a lean mass comparable to that of term infants.

Associations of Measured Protein and Energy Intakes with Growth and Adiposity in Human Milk-Fed Preterm Infants at Term Postmenstrual Age: A Cohort Study

“…-1 z-score), with the remaining infants 11.4 and 18.3 g/kg/day reported for very preterm infants in previous studies. 14,19,47 Similarly to our results, a study in preterm infants receiving early low nutrient intakes showed mean velocities varying between 9.4 and 11.3 g/kg/day. 22 Despite of the low in-hospital weight gain velocity, the body weight (0.139, p ¼ 0.205), length (0.247, p ¼ 0.681), head circumference (-0.37 cm, p ¼ 0.358), and FM% (0.469, p ¼ 0.589) of our infants at term equivalent age were similar to the values reported by Roggero et al 47 In our sample, no significant differences were found in any body composition measurement, either between sexes or between the extremely preterm and very preterm infants.…”

“…In contrast, other studies based on estimated or measured nutrient intakes found that, in preterm infants at term equivalent age, specific body compositions were associated with different nutritional strategies. In these studies, higher protein 15,19 and PER 18 intakes were associated with an increase in lean mass 18,19 and decrease in adiposity, 14 while higher fat and energy intakes were associated with increased fatness. 15 We used a nested case-control analysis to explore the associations between cumulative in-hospital nutrient intakes and extremes of adiposity 46 at term equivalent age.…”

“…12 However, in extremely and very preterm infants, studies evaluating the effects of different hospital nutritional strategies on body composition have reported conflicting results. [13][14][15][16][17][18][19] This may be explained by quite different nutritional strategies used in these infants 20 or by unknown factors. While protein and energy intakes are determinant for body composition of growing preterm infants, higher protein-toenergy ratio (PER) seems particularly relevant to avoid excessive adiposity 21 and promote FFM accretion.…”

Body composition measurements in paediatrics – a review. Part 2

“…The development of the measurement technique with the DXA method has led not only to its increased accuracy, but also its use in extreme age groups, such as infants [10] or even preterm infants [11]. Lack of age restrictions is an important advantage of DXA as compared to other two-component methods.…”

Body composition in very preterm infants during their hospital stay

“…A protein intake with a goal of 4g/kg/day in VPT infants during their first week of life had a positive association with FFM before hospital discharge (Ramel, Gray et al 2016). Protein intake with a mean of 2.9 g/kg/day during the first week of life in VPT infants had also a positive association with FFM at a mean of 39.5 weeks (Tremblay, Boudreau et al 2017). In a randomized control trial, a significant improvement in lean body weight of some 300g was seen in VPT infants at term, after the introduction of a protein intake of 3.6 g/kg/d compared to 2.7 g/kg/d (Uthaya, Liu et al, 2016).…”